The present invention relates to a chamber having an improved gas energizer.
Gas energized by electromagnetic energy, such as microwave or RF energy, is used to fabricate electronic devices on a substrate. The energized gas deposits or etches dielectric, semiconducting, and conductor materials, for example, silicon dioxide, polysilicon, metals and their suicides or nitrides on the substrate. The gas is energized by electromagnetic energy transported by a waveguide from an electromagnetic source and passed through a window into the chamber. One problem arises because it is difficult to securely attach the waveguide to the window. A secure joint between the waveguide and the window reduces the impedance of the joint to electromagnetic energy and thereby enhances coupling of electromagnetic energy through the joint. However, it is difficult to securely join the waveguide to the window without causing excessive thermal expansion stresses at their interface during processing of the substrate. Because the window is often made from brittle ceramic material, it can crack when subjected to high thermal expansion stresses. Thus it is desirable to have a secure joint between the window and the chamber that is capable of absorbing thermal expansion stresses without failing.
Another problem arises when the window heats up through the absorption of a portion of the electromagnetic energy passing through the window or because of the bombardment of energized gas onto the window. The higher window temperatures can cause the dielectric properties of the window to change and lead to inconsistent processing results. Also, higher temperatures can cause severe thermal expansion stresses at the interface between the window and chamber, which can cause failure of the joint or the window. In one solution, a heat removing device, such as a set of channels having circulating cooling fluid, is positioned abutting the window to remove heat from the window. However, the channels and fluid circulating therethrough absorbs some of the electromagnetic energy transmitted through the channels and reduces the energy coupling efficiency of the apparatus. In another solution, cooling channels are positioned around a conduit through which a as is passed for energizing the gas, and the electromagnetic energy is directed through the gaps between the channels. However, this solution also limits the electromagnetic energy that can be coupled to the gas by the size and spacing of the gaps between the channels.
Therefore there is a need for a chamber and gas energizer system that is capable of efficiently coupling electromagnetic energy to energize a gas for processing a substrate. It is also desirable to limit heating of the gas energizing components, such as the window, and to remove heat generated in the window. It is further desirable to have a chamber with a window that can withstand thermal and mechanical stresses and that can maintain a secure joint with the chamber. It is also desirable to remove the heat generated in the window to a remote location.
In one aspect, the present invention relates to a chamber capable of processing a substrate, the chamber comprising a gas distributor having an aperture through which gas may be introduced into the chamber; a wall comprising boron nitride; and a gas energizer capable of passing electromagnetic energy through the wall to energize the gas in the chamber.
In another version, the chamber comprises a gas distributor having an aperture through which gas may be introduced into the chamber; a window having a fin extending outwardly therefrom to dissipate heat from the window; and a gas energizer capable of passing electromagnetic energy through the window to energize the gas in the chamber.
In yet another version, the chamber comprises a conduit having a window comprising boron nitride, a gas energizer capable of coupling electromagnetic energy through the window to a gas in the conduit thereby generating heat in the window, and a heat sink abutting the window to remove the heat to a remote location.
In still another version, the chamber comprises a conduit comprising a as distributor having an aperture for directing a gas stream against a wall of the conduit; and a gas energizer capable of energizing the gas in the conduit.
In another version, the chamber comprises a conduit having a gas distributor through which gas may be introduced into the conduit, the gas distributor being bonded to the conduit; and a gas energizer to energize the gas in the conduit.
In another version, the chamber comprises a conduit having a passage adapted to pass gas therethrough, and a wall adjacent to the passage; a gas energizer capable of coupling energy through the wall to energize the gas in the passage; and a magnetic field generator adapted to provide a magnetic field across a portion of the wall of the conduit.
In another version, the chamber comprises a conduit through which a gas may be passed; a source of electromagnetic waves and a waveguide for transmitting the electromagnetic waves; and a surface wave generator to couple the electromagnetic waves transmitted by the waveguide to the gas in the conduit, the surface wave generator comprising one or more conductors and a movable member.
In another version, the chamber comprises a conduit through which a gas may be passed; a source of electromagnetic waves; and a waveguide adapted to transmit electromagnetic waves from the source to a surface wave generator that couples the electromagnetic waves to the gas in the conduit, the surface wave generator comprising a pair of concentric conductors, at least one conductor comprising channels through which a heat transfer fluid may be circulated.
In another version, the present invention comprises a process chamber comprising a conduit through which a gas may be passed, the conduit terminating in a gas expansion chamber having a cross-sectional area that is larger than a cross-sectional area of the conduit; and a gas energizer capable of coupling electromagnetic energy to the gas in the conduit to energize the gas.
In another aspect, the present invention comprises a method of processing a substrate in an energized gas, the method comprising the steps of energizing a gas by coupling electromagnetic energy to the gas through a window comprising boron nitride and removing the heat from the window to a remote location.
In another version, the method comprises the steps of introducing gas into a chamber; energizing the gas by coupling electromagnetic energy through a window of the chamber, whereby the window rises in temperature; and maintaining a thermal conductor in contact with the window to conduct heat away from the window.
In another version, the method comprises the steps of injecting a gas stream into a conduit at an angle relative to an axis of the conduit; and energizing the gas to process the substrate.
In another version, the method is useful for energizing a gas for processing of a substrate, and the method comprises the steps of flowing a gas through a passage of a conduit having a window; passing electromagnetic energy through the window to form an energized gas in the passage; and maintaining a magnetic field across the window to reduce impingement of the energized gas on the window.